[1] As shoshidai, he was actively and personally engaged as the head of a network of spies tasked to discover and report any covert sources of sedition, insurrection or other kinds of unrest.

When approached with a case to judge, he would place a lantern between himself and the speaker, and busy himself with making tea, so that he would not let external appearances interfere with his sense of justice.

Shigemune was expected to guard the palace and to supervise court officials; but over time, he learned that this office was no sinecure.

The merit earned by Shigemune's loyal service to the shogunate was remembered years later when devastation of the Itakura family was threatened by the otherwise unpardonable actions of a descendant.

In 1739, Hosokawa Munetake of Higo was killed inside Edo Castle by Itakura Katsukane, and the killer was ordered to commit suicide as just punishment; however, Shōgun Yoshimune personally intervened to mitigate untoward adverse consequences for the killer's fudai family.